This invention relates to dampers for air circulating systems, and in particular, to a combination of air controlling elements for use at the open end of the air handling system.
In the prior art, it is known to use air diffusers, such as grates and the like, across the open end of an air duct positioned in a wall or ceiling. It is also known to provide at some point in the air duct a fire damper, which will automatically close, usually upon actuation of a link, to restrict the flow of air through the duct under elevated temperature conditions, such as those existing during a fire.
In many air systems, it is necessary to balance the air flow, that is, to adjust the volume of air going through various air ducts. In such systems, it may be necessary to employ baffles in order to control the air flow.
In recent years, devices have been developed for re-setting fire dampers once they have been actuated and for withdrawing the resettable mechanism from outside of the damper frame by motor operated means. See, for example, the James R. Root U.S. Pat. No. 3,580,321, wherein the damper comprises a plurality of blades held in a standby position by an energized motor. The blades automatically move to the closed position when the electrical energy to the motor is interrupted. See also, my U.S. Pat. No. 3,866,656 issued Feb. 18, 1975, for folding blade fire damper (Ser. No. 357,000, filed May 3, 1973), for an improvement in such a device wherein a supplemental spring motor overcomes the frictional forces inherent in the gear operated motor. In such devices, as in all fire dampers, the folding blade damper is normally held in the open condition with the blades folded, so that it is ready to close under fire conditions. Under fire conditions, it is fully closed, that is, the blades are unfolded completely.